Advanced Engine Performance Diagnostics

19/07/2021

Staying grounded in life keeps you in charge. Okay, sorry about that.

Was called in VW Passat. Customer's complaint, the 12v battery isn't charging. My complaint, VAG harnesses suck. With the engine running and all loads on the charging voltage barely crossed 12.3v. The customer already pulled the old, pull off a battery lead test (not recommended) and car stayed running.

On further investigation we noticed the battery light didn't illuminate with KOEO. How is the light triggered? Thank you for asking. The light is triggered when it passes through the regulator in the alternator and finds ground. When the engine starts, the voltage rises and so does the ground.

So we have a situation here where: the alternator is undercharging, the car still runs when the battery lead is removed (not recommended) and the battery light is absent. After giving the old thinking meat time to marinate, I used the testlight to trigger the battery light and it worked. There's also a 12v feed for the alternator which also tested good. It kept pinging in my brain, like a Tiida on super, that the battery light didn't illuminate and it needs a ground to do so.

"Holy rectifier Batman!" It has to be a ground issue. Using my DVM, I measured 1.9v on the body of the alternator. We then took a jumper cable and clamped it to battery negative and the body of the alternator. Without hesitation the alternator began pumping voltage, like the rapper 6ix9ine pumps out crap songs. 13.8v with all loads on baby!

It turned out almost every visible ground connection was loose. Tightened them up and the Passat lived again. Harness still sucks though.

10/07/2021

Been really busy but story time is back.

Ck2 Lancer maybe? I ent your daddy! Let's call it a Ck. So a Ck with a 4g93t (GSR) comes in complaining of a check light and breakup under boost. He indicated that the light would activate at idle but deactivates with some throttle input. He also informed me that no scanners were able to enter the ecu (insert insert dirty joke here).

Anyway. Mitsubishi sort of operated on an if it ent broken don't fix it vibes, back when they made cool cars. I carried out my usual wiring foreplay and got my dinosaur of a Lanch to connect. In the ecu had tps and barro sensor codes. In the lives data, the tps was sitting at 132 mv and this was passing off the ecu by being too low. So I told the owner to buy cam, crank sensor, fuel pump and spark plugs 😅🤣😂. Just kidding!

(Serious face)

Adjusting the tps yielded minimal progress, with a max (WOT) voltage of 1345 mv. 🤔 Could it be tps is bad? I attacked the wiring with my Total (product placement) dvm. Look Total works, so don't roll up your eyes at me. On the 5v ref, I measured 1.45v 👀. That's not good. It's a "5v ref", it should be about 5v.

So, I'm at the point where I'm impressed that this car actually starts and runs. Till it beating peopl....... Nevermind. The 5v ref is shorted. How do I know? Usually anytime I've come across a 5v ref. less than 2v, a sensor has been shorted. With this knowledge, I unplugged the MAF. (Dramatic pause). The 5v came to normal level of 4.98v (good). Turned out the MAF shorted the 5v ref. which would affect all sensor inputs.

The owner should be getting a replacement soon and continue bea... Ammm.. Drive safely.

29/06/2021

Going to be working on this little beauty.

20/05/2021

Once the negative post of the battery is attached to chassis of a car, the metal parts are ground. There is no need to run a ground wire the length of the vehicle. 🤦🏿‍♂️

22/11/2020

Haltech elite + 2jzgte

15/08/2020

BMW with a hangover

30/07/2020

Been a while since I've shared a story. Fear not Covid hasn't gotten me 😁.

Had a mitsubishi 4g93 gdi with a no start today. When I got to the vehicle (8g Galant) the customer already replaced the ecm to no avail. On a scan the ecm only had fuel pressure fail code so I suspected there was fuel delivery issue. The use of throttle cleaner yielded no change in circumstances, pushing me to search out spark.

Pulling the #2 coil, I discovered spark was absent. I then checked #4 which had spark, exchanging #2's and #4's coil resulted in the same occurrence. This prompted a check on all coils. Spark was observed on #1 & #4 while #2 & #3 were dead. Using my incandescent test light I was able to make the coils on #2 & #3 fire.

The situation was pointing to an input problem (cam and/or crank sensor). Using my Uscope I read a good signal from the crank sensor but no signal from the cam sensor. After double checking respective wiring for the cam sensor it was replaced. Without the cam sensor the ecm could not sync the engine to fire all 4 coils. There were no cam sensor codes so you have to sharpen the testing skills to find this 🙄.

17/05/2020

https://youtu.be/GMJ5tJ1RyNI

Dyno discussion from one of my favorite tuners

In this video, Jeff explains the value of using a hub style dyno vs a roller style dyno and why you should have your car tuned on a hub dyno. Like us on Face...

09/05/2020

I do hope people understand this.

Why Car Engines Don't Need Back Pressure + Exhaust Scavenging Awesome Car Products: https://www.amazon.com/shop/engineeringexplained Subscribe for new videos...

08/05/2020

Keeping busy during lockdown.

06/05/2020

Pretty sure this is going to help a lot of people.

More info: https://www.platinumracingproducts.com/ After showcasing the R35 coilpack kits from PRP, you wanted to see how and why the R35 was tested and chos...